8x56

I don't know of any of the shelf solids for the 9.3. You could go to the custom loaders like kSuperior and have them load some but you would not know how they shot compared to your others either.

The best alternative is to chronograph your softs and load, or have loaded, solids to just below that velocity. Shoot them and see how they work compared to the softs and then go up or down as needed. You have 6 months and that should be plenty of time.